In the preparation of soil for planting, a disc harrow, defined as a harrow equipped with a series of sharp metal discs set on edge or at an angle on one or more axles, is frequently used as an implement. Harrows have multiple gangs of discs located independently or in groups of two or more for turning and breaking the soil. These discs are generally arranged in a wide range of configurations designed to provide maximum soil disruption over as large an area as possible in a single pass. Even so, some earth remains unbroken, including large clumps or clods. In some instances picks or breaker bars are used in combination with the disc sets or as a secondary operation to insure uniform earth disruption. Disc uniformity has long been thought to be the best method of insuring uniform soil disruption. However, uniformity has proven to be elusive requiring multiple rows of disc gangs and breakers often set at oblique angles.
Furthermore, farmers find that they must often rotate their discs to compensate for wear or exchange them when damaged. However, when discs are ganged on a single diametrically and spaced and angled accordingly to prevent soil binding between the discs. Single spindle, ganged discs generally require that all discs in a particular gang be set at the same angle of attack, therefore, most harrow discs generally have some means for changing the angulations of all discs in the gang at the same time.
In cases where single disc mountings are utilized the angle of attack may be varied but conventional wisdom and the cost of providing individual, adjustable acute angulations tends to make this feature impractical. Therefore, simultaneous angulations settings remain customary even where single disc mountings are used. Since it is desirable to maintain a consistent depth of spindle, this act becomes a time consuming chore. Discs assembled in a gang are generally all the same size cut and the discs are generally set so that the disc spindles of all gangs are set for the same dimension below the tool bars or some means is provided for raising and lowering the gangs. Any disc that is not of uniform diameter does not cut the soil to the same depth. To insure a uniform depth of cut from each disc, they must be all the same diameter or have some means for individual height adjustment. Disc depth and angle adjustment coupled with disc wear has long been a costly problem for farmers due to the time required to set both the depth and angulations of each disc and or change-out worn discs. No provision has been made for recycling worn or damaged discs.
It has long been known that a gang disc assembly set at an acute angle of attack helps prevent clogging of soil between discs upon first turning the soil. Adding a second disc gang at an obtuse angle to the first gang helps chop the soil. Such arrangements allow for circular field cultivation. Whereas inline disc gangs towed or attached in a three-point hitch arrangement located perpendicular to the direction of travel are used for back and forth field cultivation, the latter arrangement inevitably leaves irregular soil patterns near each end of the disc gangs. This requires a second or third set of ganged discs to insure proper soil disruption at each end of the disc gangs. It would therefore be advantageous to provide for maximum disruption of the soil at each end of the gangs on the first pass. This is especially advantageous if this could be done without clogging between the discs.
In addition, leveling and smoothing the broken ground, rather than simply further breaking the clods, is a desirable effect and should be accomplished during disc cultivation process. Soil levelers are currently used in secondary operations rather than in combination with the disc harrow.
Current discs are designed to rotate and are often serrated to provide a chopping effect while turning the stubble, grass, etc., under, thus exposing the roots on the surface. However, in some cases it is advantageous to cut the soil without turning the topsoil under, such as where no grass or stubble exists. In such cases rotating the soil is not only unnecessary but also detrimental by exposing the vital nutrients to the elements of wind and rain. It would therefore be advantageous to simply loosen the soil.
The invention disclosed herein addresses the issues raised above with a novel, simplistic approach.